I bought a flatbed trailer. I need to build a set of ramps. Need to know what to make them out of and sizes. Angle vs channel for the rails.

My ramps are made out of channel sides with angle cross pieces. Fairly thick steel, likely 3/16 to 1/4".

How long are we talking? This trailer a low-boy or deck over?

I forgot to ask about length, width and cleat spacing. Trailer is 20 inches to the deck. Heavest thing will be my 1954 Allis Chalmers tractor or my F250. Lowest ground clearance would be the vette.

My trailer is in storage, but I think they are 3-4 feet long. That length works great for a high clearance vehicle but not for low street cars, I end up stacking blocks and parking near a low spot. Longer ramps would be nice as long a they aren't too heavy and have support to carry your heaviest load.

Wouldn't aluminum ramps be awesome? If you could store 5ft'ers, that would be awesome!

is your trailer a dove tail? This is going to be a factor if your loading a vette & the length of ramp you decide to build/ buy. My '49 Ford rat rod that sat 5" from the ground was a bear to load even with a dove tail trailer. Had to put 2x6's, lengthwise, under the rear tires after the front apex'd the dove tail to clear the frame from dragging. Lowered vehicles are a blast to trailer, cause once in place, typically the doors hit the fricken fenders & you cant get out!!! Just my $.02